Final answer:
When a tall plant (TT) is crossed with a short plant (tt) and the F1 generation is allowed to self-pollinate, the possible phenotypes of the next generation would be tall (Tt) and short (tt).
Step-by-step explanation:
When a tall plant (TT) is crossed with a short plant (tt), the F1 generation will all be tall (Tt). If the F1 generation is allowed to self-pollinate, there are four possible combinations of factors that the F2 generation can have: TT, Tt, tT, or tt. The laws of probability suggest that 25% of the offspring would be tt and appear short, while the remaining 75% would have at least one T factor and appear tall.